What do you mean that every other genre has been forgotten ?
There are plenty of other genres that still exist other than FPS.
Platformers, RPG, Hack and Slash, Third person shooter, strategy, sidescroller .... the list goes on

For starters, what exactly is the current state of gaming? You make it seem as if somehow, even though HALO wasn't anywhere close to the first FPS, that it somehow made the entire market go full FPS games only. Last I checked, most people have been praising games like Undertale, Rise of The Tomb Raider, Yokai Watch, The Witcher, Bloodborne, and countless other titles from this year alone that don't even fit that genre.

I mean, FPS games have been a big thing since the original DOOM. It's a genre that does indeed see some big advertisement and seems to have the loudest audience overall just due to the fact that one of the biggest gaming publishers in the industry likes to cram it into your face (/looks at activision,) but that doesn't mean the industry as a whole has been dominated by this genre.

What I usually think about questions like these, is the person asking is sick and tired of seeing the, "same game every year," shoved in his face, and forgets to pay attention to the other releases that surround the one that's making a whole lot of noise. When I see this argument, I typically like to refer to it as ignoring the belligerent drunken asshole at the pub, to pay attention to all your friends and some of the good looking people around you.

To answer your question specifically in terms of Did Halo start triple A FPS shooters being a thing? Maybe, I'd like to think DOOM and Wolfenstien set the precedent, Halo carried it further, than Call of Duty slowly took over into making it a multi-million dollar a year juggernaut.

You make a game and it's successful, people are gonna want to copy it. Businesses gotta biz, you know?

So you end up with a decade's worth of "whatever"-clones that fill up the market until people get bored and move onto the next thing, and companies follow suit. Pong clones. Super Mario Bros 2D platformers. Doom clones. Wii-style motion controls. And on and on.

You make a game and it's successful, people are gonna want to copy it. Businesses gotta biz, you know?

So you end up with a decade's worth of "whatever"-clones that fill up the market until people get bored and move onto the next thing, and companies follow suit. Pong clones. Super Mario Bros 2D platformers. Doom clones. Wii-style motion controls. And on and on.

Halo was the first FPS made playable on dual analog controllers, and, by extension, consoles.

This made FPS games popular on consoles, and spawned tons of similar titles.

As the cost of game development grew, game publishers started pushing multiplatformers, in order to maximize the customer base for each game, and pushing genres and gameplay that are a) playable on all platforms, and b) a guaranteed formula for success.

This means that the games being shoved into the spotlight are GTA clones, Halo clones, and action adventure titles.

It's not down to Halo on its own, it's down to the state of the gaming industry in general.

Yeah, dual sticks, but the N64 did use the C buttons in a similar fashipn, and I actually STILL find Goldeneye's default controls to be the best for FPS games. It's a shame more games don't support full custom setups for FPS, because I'd use an inverted X and Y on the right stick all the time. Oh, and the left trigger should be default as well, since it feels much more natural.